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  Subjects -> ENGINEERING (Total: 2255 journals)
    - CHEMICAL ENGINEERING (187 journals)
    - CIVIL ENGINEERING (178 journals)
    - ELECTRICAL ENGINEERING (99 journals)
    - ENGINEERING (1203 journals)
    - ENGINEERING MECHANICS AND MATERIALS (383 journals)
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    - INDUSTRIAL ENGINEERING (60 journals)
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CHEMICAL ENGINEERING (187 journals)                     

Showing 1 - 0 of 0 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 3)
ACS Sustainable Chemistry & Engineering     Hybrid Journal  
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 4)
Acta Polymerica     Hybrid Journal   (Followers: 7)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Advanced Chemical Engineering Research     Open Access   (Followers: 12)
Advanced Powder Technology     Hybrid Journal   (Followers: 12)
Advances in Applied Ceramics     Hybrid Journal   (Followers: 4)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 21)
Advances in Chemical Engineering and Science     Open Access   (Followers: 33)
Advances in Polymer Technology     Hybrid Journal   (Followers: 12)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 8)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 5)
Applied Petrochemical Research     Open Access   (Followers: 2)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 7)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 12)
Biofuel Research Journal     Open Access   (Followers: 3)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 9)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 7)
Catalysts     Open Access   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription  
Chemical and Engineering News     Free   (Followers: 10)
Chemical and Materials Engineering     Open Access   (Followers: 3)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 10)
Chemical and Process Engineering     Open Access   (Followers: 5)
Chemical and Process Engineering Research     Open Access   (Followers: 7)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 30)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 14)
Chemical Engineering and Science     Open Access   (Followers: 5)
Chemical Engineering Communications     Hybrid Journal   (Followers: 11)
Chemical Engineering Journal     Hybrid Journal   (Followers: 21)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Research Bulletin     Open Access   (Followers: 2)
Chemical Engineering Science     Hybrid Journal   (Followers: 19)
Chemical Geology     Hybrid Journal   (Followers: 13)
Chemical Papers     Hybrid Journal   (Followers: 2)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 136)
Chemical Society Reviews     Full-text available via subscription   (Followers: 38)
Chemical Technology     Open Access   (Followers: 5)
ChemInform     Hybrid Journal   (Followers: 4)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 137)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 6)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal   (Followers: 1)
Coloration Technology     Hybrid Journal  
Computational Biology and Chemistry     Hybrid Journal   (Followers: 10)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 1)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
CORROSION     Full-text available via subscription   (Followers: 19)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 35)
Corrosion Reviews     Hybrid Journal   (Followers: 3)
Crystal Research and Technology     Hybrid Journal   (Followers: 5)
Current Opinion in Chemical Engineering     Open Access   (Followers: 4)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription  
European Polymer Journal     Hybrid Journal   (Followers: 40)
Fibers and Polymers     Full-text available via subscription   (Followers: 4)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Gels     Open Access  
Geochemistry International     Hybrid Journal   (Followers: 2)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 3)
Heat Exchangers     Open Access   (Followers: 1)
High Performance Polymers     Hybrid Journal  
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 4)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 9)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 20)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Gases     Open Access  
Info Chimie Magazine     Full-text available via subscription   (Followers: 3)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 2)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 2)
International Journal of Chemical Technology     Open Access   (Followers: 5)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 2)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 5)
International Journal of Science and Engineering     Open Access   (Followers: 4)
International Journal of Waste Resources     Open Access   (Followers: 3)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 4)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 5)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 10)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 100)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 10)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 5)
Journal of Chemical Engineering     Open Access   (Followers: 6)
Journal of Chemical Engineering and Materials Science     Open Access   (Followers: 2)
Journal of Chemical Science and Technology     Open Access   (Followers: 4)
Journal of Chemical Sciences     Partially Free   (Followers: 17)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 13)
Journal of CO2 Utilization     Hybrid Journal   (Followers: 2)
Journal of Coatings     Open Access   (Followers: 4)
Journal of Crystallization Process and Technology     Open Access   (Followers: 6)
Journal of Environmental Chemical Engineering     Hybrid Journal   (Followers: 3)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Processing & Technology     Open Access  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 4)
Journal of Fuels     Open Access  
Journal of Geochemical Exploration     Hybrid Journal  
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (Followers: 1)
Journal of Information Display     Hybrid Journal  
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 6)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 5)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 7)
Journal of Organic Semiconductors     Open Access   (Followers: 4)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 5)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 4)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 8)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 5)
Journal of Polymers     Open Access   (Followers: 2)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
Journal of Powder Technology     Open Access   (Followers: 1)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 231)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Brazilian Chemical Society     Open Access   (Followers: 2)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 1)
Journal of the Pakistan Institute of Chemical Engineers     Open Access   (Followers: 1)
Journal of the Taiwan Institute of Chemical Engineers     Hybrid Journal   (Followers: 2)
Journal of Water Chemistry and Technology     Hybrid Journal   (Followers: 8)
Jurnal Inovasi Pendidikan Kimia     Open Access  
Jurnal Reaktor     Open Access  
Jurnal Teknologi Dan Industri Pangan     Open Access   (Followers: 1)
Korean Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 1)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 14)
Materials Science and Applied Chemistry     Open Access  
Materials Sciences and Applied Chemistry     Full-text available via subscription  
Molecular Imprinting     Open Access  
MRS Communications     Hybrid Journal  
Nanocontainers     Open Access  
Nanofabrication     Open Access  
Noise Control Engineering Journal     Full-text available via subscription   (Followers: 2)
Ochrona Srodowiska i Zasobów Naturalnych : Environmental Protection and Natural Resources     Open Access  
Petroleum Chemistry     Hybrid Journal   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 3)
Plasma Processes and Polymers     Hybrid Journal  
Plasmas and Polymers     Hybrid Journal  
Polymer     Hybrid Journal   (Followers: 90)
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 13)
Powder Technology     Hybrid Journal   (Followers: 12)
Recyclable Catalysis     Open Access   (Followers: 1)
Research on Chemical Intermediates     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 5)
Revista Cubana de Química     Open Access  
Revista ION     Open Access  
Revista Mexicana de Ingeniería Química     Open Access  
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Bulletin     Hybrid Journal   (Followers: 2)
Russian Journal of Applied Chemistry     Hybrid Journal   (Followers: 1)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 54)
Solid Fuel Chemistry     Hybrid Journal  
South African Journal of Chemical Engineering     Open Access   (Followers: 2)
South African Journal of Chemistry     Full-text available via subscription   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 5)
Sustainable Chemical Processes     Open Access   (Followers: 1)
Synthesis Lectures on Chemical Engineering and Biochemical Engineering     Full-text available via subscription  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
The Chemical Record     Hybrid Journal   (Followers: 1)
Theoretical Foundations of Chemical Engineering     Hybrid Journal   (Followers: 2)
Transition Metal Chemistry     Hybrid Journal   (Followers: 2)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Visegrad Journal on Bioeconomy and Sustainable Development     Open Access   (Followers: 1)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)

           

Journal Cover Chemical Engineering Science
  [SJR: 1.178]   [H-I: 114]   [19 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [2970 journals]
  • Using microchannels to visually investigate the formation and dissolution
           of acrylonitrile droplets in a bio-hydration system
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Jiahui Li, Yang Chen, Mingzhao Guo, Yujun Wang, Jianhong Xu, Guangsheng Luo, Huimin Yu
      Coaxial microfluidic devices were used to investigate the formation of acrylonitrile droplets and the dissolution of acrylonitrile during the droplet generation stage in a bio-hydration system. The average mass transfer coefficient of acrylonitrile was obtained using an online visual measurement method. The average mass transfer coefficient of acrylonitrile in water increased from 3.91×10−3 to 11.80×10−3 m/s and the droplet size decreased from 85 to 55μm when the flow rate of the continuous phase was increased from 40 to 200μL/min. In contrast, the average mass transfer coefficients of acrylonitrile in a 900U/mL free-cell solution ranged from 5.95 to 14.56×10−3 m/s under the same conditions, while the bio-reaction rarely affected the size of the generated droplet. In addition, the increase of the acrylamide concentration changed the flow pattern from the dripping regime to jetting and laminar regimes and significantly reduced the droplet size.


      PubDate: 2016-06-26T09:31:11Z
       
  • Numerical analysis of gasification and emission characteristics of a
           two-stage entrained flow gasifier
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Bo Zhang, Zhuyin Ren, Shaoping Shi, Shu Yan, Fang Fang
      A two-stage dry-feed oxygen-blown entrained flow gasifier of HNCERI (Huaneng Clean Energy Research Institute) has been numerically studied through an integrated CFD-ROM approach, in which computational fluid dynamics (CFD) simulation is employed to investigate the detailed flow, temperature and composition fields, as well as to provide necessary information for the construction of reactor network-based reduced order model (ROM). A 10-step gasification chemistry together with an eight-step pollutant formation model optimized for the HNCERI gasifier have been constructed to investigate the gasification characteristics and emission of NO x , NH3, HCN, COS, SO2 etc. Computational results show that a ROM consisting of two perfectly stirred reactors and one plug flow reactor can accurately reproduce the available gasification and emission industrial data in minutes on a PC and thus is suitable to integrate with process flowsheet simulation. Heterogeneous reactions are found to dominate the gasification process in the second stage of the gasifier. The CO/H2 distribution in product syngas is determined by the water gas shift reaction at the downstream of the second stage where it reaches equilibrium. A sensitivity analysis shows that the coal and oxygen feed rates have pronounced effects on gasification characteristics while the effects of the steam feed rate and pressure are minimal. In addition, the decrease in the ratio of the coal feed rate of the second stage to the total coal feed rate may further increase the gasification efficiency, the effective gas production rate and carbon conversion with slight decrease in the temperature within the gasifier.


      PubDate: 2016-06-26T09:31:11Z
       
  • The optimal diffusion experiment
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): L. Wolff, H.-J. Koß, A. Bardow
      Diffusion experiments are time-consuming and expensive. Therefore, diffusion experiments should be designed such that they allow for efficient measurements while still leading to high accuracy of the diffusion coefficients. Numerous experimental setups have been designed in the past centuries incorporating a variety of geometries. The accuracy of experimentally determined diffusion coefficients depends on the geometry of the experimental setup as well as on the analytical techniques used to determine concentrations of the diffusion species. Whereas analytical techniques and their accuracy are subject of continuous improvement, geometries are genuine features of a setup. Therefore, optimal geometries for diffusion experiments can be identified once and for all. In this work, we identify optimal geometries to measure diffusion coefficients. For this purpose, we analyze the influence of the geometry of an experimental setup on the accuracy of the determined Fick diffusion coefficients. We consider both already existing and theoretically conceivable geometries. The analysis is based on the method of model-based optimal experimental design. Open geometries, where components can diffuse out of the geometry, are identified to be most beneficial. The most commonly employed free diffusion experiments are shown to lead to high uncertainty. Replacing free diffusion experiments by experiments with open geometries can improve the accuracy of the Fick diffusion coefficients by up to two orders of magnitude. We show that the optimal geometries are robust with respect to uncertainties in the diffusion coefficient as well as with respect to uncertainties in measurement positions, measurement times and positions of the initial domain boundary.


      PubDate: 2016-06-26T09:31:11Z
       
  • Prediction of vapor–liquid equilibria for mixtures of low boiling
           point compounds using Wong–Sandler mixing rule and EOS/GE model
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Reza Espanani, Andrew Miller, William Jacoby
      Vapor–liquid equilibrium (VLE) of low boiling point components occurs at low-temperature and usually at high pressure. A proper method for computing the fugacity coefficient is to use a cubic equation of state with mixing rules. However, empirical mixing rules include one adjustable parameter and cannot predict VLE of some mixtures accurately. An alternative that could be used for non-ideal mixtures is the Wong–Sandler mixing rule, which is derived based on the excess Gibbs energy (GE ). In this research, VLE of light gaseous mixtures was calculated at low temperatures and medium to high pressures using the Peng–Robinson equation of state (PR EOS), the Wong–Sandler mixing rule, and the NRTL equation as a GE model. This introduces an additional adjustable parameter. Assuming the adjustable parameters as a function of temperature, the results show that this thermodynamic model is an appropriate method to predict VLE of low boiling point materials at wide range of temperatures.


      PubDate: 2016-06-26T09:31:11Z
       
  • First investigation of modified poly(2-vinyl-4,4-dimethylazlactone)s as
           kinetic hydrate inhibitors
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Lilian H.S. Ree, Malcolm A. Kelland, Peter J. Roth, Rhiannon Batchelor
      A series of polymers of 2-vinyl-4,4-dimethylazlactone (VDMA) of varying molecular weights modified with small organic amines have been synthesized. Their performance as kinetic hydrate inhibitors (KHIs) has been investigated in high pressure steel rocking cells using a Structure II-forming synthetic hydrocarbon gas mixture. It was found that the PVDMA polymer with the lowest molecular weight (Mn=1845g/mole by 1H NMR) performed the best. It was also found that the n-propylamine derivative performed the best of the amine derivatives. The cloud point of this polymer derivative was found to be lower than ambient temperature, which is considered too low for practical oilfield applications. However, high cloud point PVDMA derivatives such as the ethylamine or pyrrolidine derivatives still gave reasonable KHI performance. The KHI performance of the n-propylamine derivative of PVDMA-I was tested at different concentrations in the range 1000–7000ppm. It was found that the performance improved as the polymer concentration was increased.


      PubDate: 2016-06-26T09:31:11Z
       
  • Investigation of bubble swarm drag at elevated pressure in a contaminated
           system
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): C.D. Lane, V. Parisien, A. Macchi, A.A. Donaldson
      Improved estimates of bubble dynamics in industrial gas-liquid fluid systems are important for accurately modeling multiphase flow. In many gas-liquid industrial systems at elevated pressure, bubbles exist in a polydisperse size population. This work experimentally characterizes the effects of bubble swarm polydispersity and gas holdup on drag using a monofibre optical probe in an ethanol contaminated aqueous system, providing an evaluation of current swarm drag models under industrially relevant pressures and high gas holdup conditions (up to 37% gas fraction). At atmospheric pressure, the rise velocity and swarm-corrected drag of individual bubbles within a polydisperse distribution of bubbles was found to be well-predicted by the swarm correction model of Lockett and Kirkpatrick (1975). An improved fit to the reported data was found using a piecewise isolated single bubble drag coefficient correlation. At elevated pressures (6.5MPa), swarm hindrance effects were not observed for detected bubbles and the rise velocity and drag coefficient of individual bubbles within a polydisperse distribution were well predicted without the use of a swarm correction model.


      PubDate: 2016-06-26T09:31:11Z
       
  • A heuristic approach based on a single-temperature-peak design principle
           for simultaneous optimization of water and energy in fixed flowrate
           systems
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Wanni Xie, Yanlong Hou, Yuxin Wang, Jingtao Wang
      Methods of process integration could be classified in to two categories: the mathematical and conceptual method. The former is outstanding to solve the overall simultaneous synthesis problems, but sometimes, complex calculations will be needed. The conceptual method also could be employed to solve the problem about simultaneous optimization of water and energy but few of them could deal with the multiple contaminants problems. In this paper, a new heuristic approach is proposed to optimize simultaneously the water allocation and heat-exchange network (WAHEN) with both single and multiple contaminants in a fixed flowrate (FF) system. In order to build up this approach solidly, a principle of the single-temperature-peak design is proved through pinch analysis which discloses the interactions between water allocation network (WAN) and energy exchange network (HEN). When WAN only has a single-temperature-peak for each sub-stream, the heat recovery problem of this system could be a threshold problem requiring less energy. As a trade-off between water and energy consumption is established in this design principle, the water and energy consumption could be optimized at one step. Based on this single-temperature-peak design, a novel heuristic approach including two main designing steps, the design of WAN and HEN, is established. A graphical method is employed to design the original water allocation network to ensure it to be a single-temperature-peak type. Next, based on this WAN, WAHEN structures are further generated, which employs a method ensuring that the total energy consumption equals to the minimal value calculated by the first step. Graphical visualization is the advantage of this methodology, and it does not need complex mathematical calculations. Four literature examples are employed to check this new method. That the obtained optimization results are better than those of other works proves its effectivity and advantage. Currently, this paper mainly focuses on the water-reusing network, not the total network which will be investigated in our next work.


      PubDate: 2016-06-26T09:31:11Z
       
  • Modeling a production scale milk drying process: parameter estimation,
           uncertainty and sensitivity analysis
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): A. Ferrari, S. Gutiérrez, G. Sin
      A steady state model for a production scale milk drying process was built to help process understanding and optimization studies. It involves a spray chamber and also internal/external fluid beds. The model was subjected to a comprehensive statistical analysis for quality assurance using sensitivity analysis of inputs/parameters, and uncertainty analysis to estimate confidence intervals on parameters and model predictions (error propagation). Variance based sensitivity analysis (Sobol's method) was used to quantify the influence of inputs on the final powder moisture as the model output. Bayesian Inference using Markov Chain Monte Carlo sampling was used to quantify the uncertainty on the estimated parameters using available process data. In a full scale process the inputs with major range of variation are: moisture content at concentrate chamber feed (variation around 4%), and humidity at chamber inlet air (variation > 100%). The sensitivity analysis results suggest exploring improvements in the current control (Proportional Integral Derivative) for moisture content at concentrate chamber feed in order to reduce the output variance. It is also confirmed that humidity control at chamber inlet air stream would not be necessary because, despite its wide range of variation (air taken from outside), its impact on output variance is low. The uncertainty analysis results showed that confidence intervals obtained for parameters were reasonable, although some of them were found significantly correlated. For model applications, this means that model simulations should be performed using not only parameter values but also their correlation matrix by means of non-linear error propagation methods such as Monte Carlo techniques. The separate effects on model prediction uncertainties due to parameter estimation and measurement errors were studied. The results indicate that the error in measurements is the main responsible for the uncertainty in output predictions. Therefore using proper filtering of measurements, the comprehensively tested model is ready to support simulation based efforts for further process optimization.


      PubDate: 2016-06-26T09:31:11Z
       
  • Vacuum powder feeding and dispersion analysis for a solar thermochemical
           drop-tube reactor
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Majk Brkic, Erik Koepf, Ivo Alxneit, Anton Meier
      Ultrasonic vibratory and rotary valve particle feeders have been designed, constructed, and investigated for application to feeding reactant powder to a solar thermochemical drop-tube reactor. Zinc oxide and carbon particles are fed continuously to the drop-tube under vacuum pressures as low as 1mbar. The particles are probed in situ by laser transmission measurements with the aim to characterize particle residence time, axial and radial dispersion as a function of operating pressure. The ultrasonic feeder disperses particles well and can be operated at mass flow rates in the range of 57–288mgmin−1. The rotary valve feeder operates in the mass flow range of 3.46–41.96gmin−1 and exhibits reduced particle dispersion due to discrete pulsing mass flow created from the rotating valve. The time resolved transmission signals reflect characteristic changes under different experimental vacuum conditions. Particles traveling through the measurement zone at 1mbar exhibit residence and clearance times of 0.05s and 0.52s, respectively. At 960mbar, residence and clearance times are increased to as much as 0.16s and 3.98s, respectively. Particles falling at 1mbar show radial dispersion three times less than those falling under ambient pressure. A critical result of the functional characterization of powder feeding under vacuum is a potential reaction capacity limitation at low vacuum pressures due to short particle residence time and narrow axial dispersion.
      Graphical abstract image

      PubDate: 2016-06-26T09:31:11Z
       
  • Implementation of an improved bubble breakup model for TFM-PBM simulations
           of gas–liquid flows in bubble columns
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Xiaofeng Guo, Qiang Zhou, Jun Li, Caixia Chen
      An improved bubble coalescence and breakup model was implemented in the inhomogeneous TFM-PBM model for buoyancy-driven gas–liquid bubbly flows. The bubble coalescence was modeled by considering bubble collisions induced by turbulent fluctuations, buoyancy driven, wake entrainment, and viscous shear, and the liquid film drainage model was used for the description of the coalescence efficiency of collisions. The bubble breakup was analyzed in terms of bubble interactions with turbulent eddies which coupled the restriction of surface energy with the capillary pressure. A generic TFM-PBM model was developed and applied for the simulations of bubble columns operated in different flow regimes. The evolutions of the bubble size distributions were simulated and validated for literature data of a D=0.14m cylindrical bubble column at gas superficial velocities 0.03 and 0.45m/s, respectively. Furthermore, a well documented D=0.44m bubble column was simulated, and the predicted distributions of the gas holdup and liquid velocity were compared with the experimental measurements of Chen et al. (1998). The model showed the capacity of describing the gas–liquid fluid dynamics of bubble columns operated in both bubbly and churn-turbulent flow regimes.


      PubDate: 2016-06-26T09:31:11Z
       
  • Overproduction of squalene synergistically downregulates ethanol
           production in Saccharomyces cerevisiae
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Aamir Rasool, Muhammad Saad Ahmed, Chun Li
      Metabolic engineering strategies are often devised to redirect precursor flux in an engineered pathway. To develop a new strategy, the effect of overexpression of the squalene biosynthesis (SB) pathway and squalene overproduction on the ethanol production (EP) and post-squalene biosynthesis (PB) pathways was determined in Saccharomyces cerevisiae. Through overexpression of the HMG1, IDI1, ERG20 and ERG9 genes of the SB pathway, production of squalene increased 10-fold in the M1EG strain compared to the wild-type strain (WT) [(34mg/L), without terbinafine, an inhibitor of squalene monooxygenase, and 35.02-fold (119.08mg/L) with terbinafine]. However, due to overexpression of the SB pathway and squalene overproduction, production of ethanol and functionality of the EP and PB pathways were synergistically downregulated by 51.61%, 95.86% and 81.79%, respectively, in the M1EG strain compared to the WT strain. Overexpression of the entire SB pathway also enhanced production of squalene by 76.12-fold (304.49mg/L) and synergistically downregulated production of ethanol and functionality of the EP and PB pathways by 66.13%, 97.02% and 87.56% in the FOH-2 strain compared to the WT strain, respectively. The EP and PB pathways were strongly downregulated in the FOH-2 strain compared to the M1EG strain because the FOH-2 strain overexpresses the entire SB pathway and produces more squalene than the M1EG strain. These data suggest that overexpression of the SB pathway and squalene overproduction downregulate the EP and PB pathways in engineered strains. Therefore, we speculate that a cryptic regulation mechanism may downregulate these pathways, and characterization of such a mechanism may enable us to divert the precursor flux from the EP and PB pathways to the squalene biosynthesis pathway.


      PubDate: 2016-06-26T09:31:11Z
       
  • An improved Front-Tracking technique for the simulation of mass transfer
           in dense bubbly flows
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): I. Roghair, M. Van Sint Annaland, J.A.M. Kuipers
      Direct numerical simulation results of mass transfer in dense bubble swarms using a Front-Tracking (FT) model will be presented, where the effect of the gas hold-up has been investigated. The FT method is particularly suited for bubble swarm simulations, since bubbles do not coalesce artificially, but traditional FT techniques often suffer from artificial volume loss of the bubbles. For this reason, a specialized remeshing technique is presented to counteract any occurring volume defects, while keeping all physical undulations on the bubble surfaces unharmed. For the simulation of gas-to-liquid mass transfer, a species transport equation (convection–diffusion–reaction) was coupled to the FT hydrodynamics solver, which was solved on a superimposed refined mesh for higher accuracy. The velocity components have been interpolated to the refined grid using a higher-order solenoidal method. Enforcement of the Dirichlet condition for the concentration at the gas–liquid interface is achieved with an immersed boundary method, enabling the description of gas to liquid mass transfer. Careful validation of the newly implemented model shows satisfactory results. The liquid side mass transfer coefficient in dense bubble swarms, with gas fractions between 4% and 40%, has been investigated using the new model. The simulations have been performed in a 3D domain with periodic boundaries, mimicking an infinite swarm of bubbles. The results indicate that the liquid-side mass transfer coefficient rises only slightly with increasing gas fraction.
      Graphical abstract image Highlights

      PubDate: 2016-06-26T09:31:11Z
       
  • Controlled formation and coalescence of paramagnetic ionic liquid droplets
           under magnetic field in coaxial microfluidic devices
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Jin-Pei Huang, Xue-Hui Ge, Jian-Hong Xu, Guang-Sheng Luo
      This article reports the scaling law of droplet formation of the paramagnetic ionic liquid (MIL) under magnetic field in a coaxial microfluidic device. Firstly, the effect of two phase flow rates and magnetic forces on the size of MIL droplet in a coaxial microfluidic device were studied systematically. Then, based on force analysis, a mathematical model for the prediction of the diameter of MIL droplets was developed. Furthermore, a novel method which can achieve in-situ formation and controlled coalescence of droplets was developed by using a designated magnetic field.


      PubDate: 2016-06-26T09:31:11Z
       
  • Forced convective transport of alumina–water nanofluid in
           micro-channels subject to constant heat flux
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Chen Yang, Kanglei Peng, Akira Nakayama, Ting Qiu
      A modified Buongiorno model of nanofluids was established with full considerations of scaling effects and four driving mechanisms of nanoparticles migration in micro-channels. In order to reveal nanoparticles migration, heat transfer and pressure drop characteristics of alumina–water nanofluid in hydrodynamically and thermally fully developed region of micro-channels, the proposed governing equations were solved by means of the Runge-Kutta-Gill method. The obtained results demonstrated that the viscous dissipation term exhibits adverse influence on heat transfer performance for heating and cooling cases. Moreover, it has been found that the increase of the amount of slip velocity and temperature jump at the wall not only enhances heat transfer, but also decreases pressure drop, indicating promising application prospects of nanofluids in micro-channels. Eventually, four driving mechanisms of nanoparticles migration are discussed. The results clearly indicated that Brownian diffusion and thermophoresis are more important than shear-induced diffusion and viscosity gradient-induced diffusion.


      PubDate: 2016-06-26T09:31:11Z
       
  • Experimental study on drag reduction performance of surfactant flow in
           longitudinal grooved channels
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Chonghai Huang, Dongjie Liu, Jinjia Wei
      Drag-reducing surfactant solution can provide a large-eddy environment for longitudinal microgrooves and may realize the complementarity between their drag-reduction mechanisms. In this work, the collaborative drag reduction performance of surfactant solution and longitudinal microgrooves was experimentally studied to verify the speculation about their complementary possibility. The mixture aqueous solution of cationic surfactant (cetyltrimethyl ammonium chloride) and counterion salt (NaSal) was tested in the smooth and two longitudinal microgroove channels respectively at the mass concentrations of 0.16–0.47mmol/L. It was found that the drag reduction performance of surfactant solution was enhanced by the longitudinal microgrooves. The drag-reduction mechanisms of microgrooves in water and surfactant solution were illustrated by the competition between the “peak effect” and the “restriction effect” of microgroove. Moreover, the “second peak effect” was proposed to explain the drag-reduction enhancement mechanisms for surfactant flow in microgroove channels. The groove with a larger size and roughness which might increase the drag in water could still enhance the drag reduction effectiveness of surfactant flow, and had a lower critical temperature and critical Reynolds number in surfactant solution, indicating a promising application in the heat transfer and drag reduction field. Moreover, the results of particle image velocimetry of smooth channel indirectly verified that the drag-reducing mechanism of microgroove was related to the turbulent vortex scale and the restriction effect on near-wall vortices.


      PubDate: 2016-06-26T09:31:11Z
       
  • An integrated two-step Fr 13 synthesis - demonstrated with membrane
           fouling in combined ultrafiltration-osmotic distillation (UF-OD) for
           concentrated juice
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Wei Zou, Kenneth R. Davey
      Here we synthesize a two-step Fr 13 risk assessment (Davey et al., 2015; Davey, 2015) for the first time. We demonstrate it with vulnerability to fouling in an apparent steady-state global process of integrated cross-flow ultrafiltration and osmotic distillation (UF-OD) for concentration of fruit juice. Integrated two-step membrane processing of juices is becoming widespread as an alternative to thermal treatment. The aim was to advance the Fr 13 framework to investigate how naturally occurring, random fluctuations in apparent steady-state plant parameters can be transmitted and impact in progressively multi-step complex (i.e. integrated not ‘complicated’) processes. Membrane behavior is simulated using Monte Carlo (with Latin Hypercube) sampling of transmembrane pressure (∆P UF 1-1) and filtration time (t UF 1-1) with independent data for concentrating pomegranate juice (Punica granatum). Membranes fouling is defined as a permeate flux less than the operational design flux. Overall global failure of the integrated two-step UF-OD is defined as an unwanted OD flux (J OD 1-2<J OD 1-2, required plus 3% tolerance). Results show the Fr 13 method is applicable to an integrated two-step process. The integrated UF-OD is expected to be vulnerable to surprise fouling in 10.5% of all operations, over an extended time. Findings are used to assess re-design for reduced membrane vulnerability to fouling in second-tier studies. Results appear generalizable and could be applied to a range of integrated two-step processing. Outcomes will be of interest to risk analysts and manufacturers of membrane equipment. This work is part of an overall development and investigation of Fr 13 as a new quantitative risk assessment and equipment design tool.
      Graphical abstract image

      PubDate: 2016-06-26T09:31:11Z
       
  • Influence of orifice type and wetting properties on bubble formation at
           bubble column reactors
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): M. Huber, D. Dobesch, P. Kunz, M. Hirschler, U. Nieken
      We show a direct numerical simulation (DNS), which is capable of describing immiscible two-phase flow including surface tension and the dynamics of partial wetting. Our investigation focuses on the initial bubble formation process at the inlet and analyzes the dynamics of the bubble detachment. It is shown, how orifice geometry and wetting properties influence size and surface of the bubble. This approach has a high potential for liquid–liquid reactions and high pressure gas–liquid reactions. The use of different materials for an orifice like stainless steel or ptfe is considered by taking their distinct wetting properties into account. The investigated orifice types range from an injector nozzle over a regular capillary to a diffuser. Furthermore the influence of different volume fluxes in the feed is analyzed and a systematic comparison with respect to a desired bubble volume is given. The physical model is implemented in the Lagrangian smoothed particle hydrodynamics (SPH) method, which is, due to its mesh-free nature, particularly suitable for moving interfaces.


      PubDate: 2016-06-17T18:01:14Z
       
  • Numerical simulation of 3D hollow-fiber vacuum membrane distillation by
           computational fluid dynamics
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Yonggang Zhang, Yuelian Peng, Shulan Ji, Shaobin Wang
      Computational fluid dynamics (CFD) was employed for modeling and simulation of the heat and mass transfer processes in hollow-fiber vacuum membrane distillation (VMD) under laminar flow conditions. A three-dimensional VMD model was first developed and validated by coupling the latent heat with the energy conservation equations and experimental data. Then it was used to analyze the effects of operating conditions and module dimensions on local temperatures, heat transfer coefficients, temperature polarization coefficients, heat and mass fluxes and total thermal efficiency in an operation of the feed flowing in the lumen of the fibers and the shell in vacuum. Thermal efficiency varied with feed temperature and feed velocity. Temperature polarization became more significant at high feed temperature and low feed velocity. Mass transfer was controlled by the heat transfer in the feed boundary. Local heat and mass fluxes decreased along the fiber length because of high local heat transfer coefficient in the inlet region and thin thermal boundary. More importantly, total thermal efficiency decreased with increasing module length, thus a short module was better used for high efficiency of VMD.


      PubDate: 2016-06-17T18:01:14Z
       
  • Development of a gas–solid drag law for clustered particles using
           particle-resolved direct numerical simulation
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Mohammad Mehrabadi, Eric Murphy, Shankar Subramaniam
      Particle-resolved direct numerical simulation (PR-DNS) is used to quantify the drag force on clustered particle configurations over the solid phase volume fraction range of 0.1 ≤ ϕ ≤ 0.35 and the mean slip Reynolds number range of 0.01 ≤ Re m ≤ 50 . The particle configurations and flow parameters correspond to gas–solid suspensions of Geldart A particles in which formation of clusters have been reported. In our PR-DNS, we use clustered particle configurations that match cluster statistics observed in experimental studies. To generate the particle configurations, we perform discrete element method (DEM) simulations of homogeneous cooling gas (HCG) systems with cohesive and inelastic particles in the absence interstitial fluid. Clustered particle sub-ensembles are then extracted from HCG simulations to match the statistics of cluster size distributions observed in experiments. These sub-ensembles are used for PR-DNS. It is found that the mean drag on clustered configurations decreases when compared to the drag laws for uniform particle configurations. The maximum drag reduction is observed in the configuration with low solid-phase volume fraction ϕ = 0.1 in Stokes flow, and is about 35 % . The drag reduction reduces with increase in both ϕ and Re m . A clustering metric is introduced to explain the behavior of the drag reduction with respect to solid-phase volume fraction. Also the behavior of the drag reduction with mean slip Reynolds number is related to the Brinkman screening length. PR-DNS results are then used to propose a clustered drag model for the range of flow parameters considered in this study. This clustered drag model provides a smooth transition between the uniform and clustered states by means of a weighting function with two model parameters.


      PubDate: 2016-06-17T18:01:14Z
       
  • The shape and behaviour of a granular bed in a rotating drum using
           Eulerian flow fields obtained from PEPT
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): A.J. Morrison, I. Govender, A.N. Mainza, D.J. Parker
      Non-invasive single-particle tracking techniques, such as positron emission particle tracking (PEPT), provide useful information about the behaviour of a representative particle moving in a bulk of similar particles in a rotating drum. The Lagrangian trajectories that they yield can be used to study, for example, particulate diffusion or granular interaction. However, often the Eulerian flow fields of the entire granular bed are more useful– they can be used to study segregation, for instance, or the evolution of the free surface of the bed. In this work, we present a technique for converting Lagrangian trajectories to Eulerian flow fields via a time-weighted residence time distribution (RTD) of the tracked particle. We then perform PEPT experiments on a mono-disperse bed of spherical particles in a cylindrical drum, rotated at various rates, and use the RTD procedure to obtain flow fields of the bed. We use these flow fields to investigate the effect of drum rotational speed on the shape and behaviour of a granular bed in a rotating drum, and the insights gained thereby to define a comprehensive set of surfaces– such as the bulk free surface– to divide the bed into regions of distinct granular behaviour. We further define scalar bed features– such as the centre of circulation of the bed– that can be used to quantitatively compare the behaviour of granular beds in rotating drums operated under various conditions.
      Graphical abstract image Highlights fx1

      PubDate: 2016-06-17T18:01:14Z
       
  • A new turbulence-induced theoretical breakage kernel in the context of the
           population balance equation
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Sandipan Kumar Das
      The current paper develops a new breakage kernel for use in the population balance equation. The study properly accounts for the direction of the relative velocity of the eddy and determines the size of the daughter bubble from the angle at which the eddy hits the parent bubble and its orientation at the point of impact. The breakup kernel considers both the capillary pressure of the parent bubble and the surface energy increase of the daughter bubbles in its formulation. The model predictions agree very well with the experimental data available in the literature. A parametric study of the breakage kernel further analyzes its behavior over a range of flow conditions. The parameterization also leads to a simplified breakage kernel.


      PubDate: 2016-06-17T18:01:14Z
       
  • The flow inside shaking flasks and its implication for mycelial cultures
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): C. Palacios-Morales, J.P. Aguayo-Vallejo, M.A. Trujillo-Roldán, R. Zenit, G. Ascanio, M.S. Córdova-Aguilar
      Several parameters such as mixing time, power consumption and deformation rates have been commonly reported in the literature for the hydrodynamic characterization of shaken flasks. In the present work, flow fields of orbital shaken flasks having different geometries have been experimentally obtained. Conventional, baffled and coiled flasks were tested at constant shaking speed of 150rpm at which the cultures are grown. Flow fields in terms of turbulence intensity and deformation rate were both determined by means of the Particle Image Velocimetry (PIV) technique. Velocity fields are strongly dependent on the flask geometry; in particular, the main flow is confined near the wall for the conventional geometry. In general, large velocity fluctuations are found in the whole flask for the baffled and coiled geometries, while the turbulence intensity is virtually zero at the center region for the conventional flask. The measurement of the average deformation rate indicates that flow obstacles, such as indentations and coiled springs, generate regions with high hydrodynamic stresses promoting the elongation and breakup of bubbles and biomass. Results from this study have been compared with previous studies finding good agreement for the same flask configurations at similar experimental conditions.
      Graphical abstract image Highlights fx1

      PubDate: 2016-06-17T18:01:14Z
       
  • Mass transfer into a spherical bubble
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): A. Saboni, S. Alexandrova, M. Karsheva, C. Gourdon
      A numerical study has been conducted to investigate the mass transfer inside a spherical bubble at low to moderate Reynolds numbers. The Navier–Stokes and diffusion–convection equations were solved numerically by a finite difference method. The effect of the bubble Schmidt number (over the range 0.1<Scd <5) and of the internal Reynolds number (over the range 0.1<Red <13) on mass transfer is investigated. The results show that the mass transfer is strongly dependent on the Reynolds number and the Schmidt number. From the numerical results, a predictive equation for the Sherwood number in terms of the Schmidt number and the Reynolds number is derived.


      PubDate: 2016-06-13T12:47:17Z
       
  • Bubble swarm rise velocity in fluidized beds
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Miroslav Puncochar, Marek C. Ruzicka, Miroslav Simcik
      New formulas are suggested for the swarm speed of cap-shaped gas bubbles collectively rising within a gas–solid fluidized bed. Their derivation stems from comparing the added mass of a single bubble and a swarm of bubbles: U B U 0 = C 0 C . For different flow conditions, there are different trends in the dependence of the added mass on the bubble concentration (voidage). This variance translates into different predictions of the suggested swarm speed formulas. This difference is explained in terms of the geometrical configuration of bubbles inside the bed. The expressions for the added mass coefficient in case of two typical flow regimes are introduced: C = C 0 ( 1 − ε ) freely bubbling regime , C = C 0 ( 1 − ε ) 2 near slugging regime .
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Coupled gel spreading and diffusive transport models describing
           microbicidal drug delivery
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Claire Funke, Kelsey MacMillan, Anthony S. Ham, Andrew J. Szeri, David F. Katz
      Gels are a drug delivery platform that is being evaluated for application of active pharmaceutical ingredients, termed microbicides, that act topically against vaginal and rectal mucosal infection by sexually transmitted HIV. Despite success in one Phase IIb trial of a vaginal gel delivering tenofovir, problems of user adherence to designed gel application scheduling have compromised results in two other trials. The microbicides field is responding to this dilemma by expanding behavioral analysis of the determinants of adherence while simultaneously improving the pharmacological, biochemical, and biophysical analyses of the determinants of microbicide drug delivery. The intent is to combine results of these two complementary perspectives on microbicide performance and epidemiological success to create an improved product design paradigm. Central to both user sensory perceptions and preferences, key factors that underlie adherence, and to vaginal gel mucosal drug delivery, that underlies anti-HIV efficacy, are gel properties (e.g. rheology) and volume. The specific engineering problem to be solved here is to develop a model for how gel rheology and volume, interacting with loaded drug concentration, govern the transport of the microbicide drug tenofovir into the vaginal mucosa to its stromal layer. These are factors that can be controlled in microbicide gel design. The analysis here builds upon our current understanding of vaginal gel deployment and drug delivery, incorporating key features of the gel's environment, the vaginal canal, fluid production and subsequent gel dilution, and vaginal wall elasticity. These have not previously been included in the modeling of drug delivery. We consider the microbicide drug tenofovir, which is the drug most completely studied for gels: in vitro, in animal studies in vivo, and in human clinical trials with both vaginal or rectal gel application. Our goal is to contribute to improved biophysical and pharmacological understanding of gel functionality, providing a computational tool that can be used in future vaginal microbicide gel design.


      PubDate: 2016-06-13T12:47:17Z
       
  • Table of Contents
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151




      PubDate: 2016-06-13T12:47:17Z
       
  • Dynamic vertical forces working on a large object floating in
           gas-fluidized bed: Discrete particle simulation and Lagrangian measurement
           
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Kyohei Higashida, Kenta Rai, Wataru Yoshimori, Tomoki Ikegai, Takuya Tsuji, Shusaku Harada, Jun Oshitani, Toshitsugu Tanaka
      In a number of practical applications of fluidized bed, large solid objects coexist with small bed materials and the prediction of large objects’ motion in fluidized is quite important. In the present study, we investigate the dynamic vertical forces working on a large sphere floating in a three-dimensional bubbling gas-fluidized bed. Numerical results obtained by using Fictitious particle method (FPM) are directly compared in detail with experimental results obtained by a non-invasive Lagrangian sensor system which can directly measure forces working on a free-moving object. In the present condition, the sphere keeps on floating near the free surface of the bed during fluidization and it shows characteristic upward and downward motions. Time-series data of the dynamic vertical forces agrees reasonably well between the simulation and the experiment and its quasi-periodicity and intermittent occurrence of characteristic peaks are confirmed. The mean and standard deviation of the dynamic vertical forces show good agreements between the simulation and the experiment with some differences in distributions of the relative frequency. From the numerical results, we confirm that the fluctuation of forces is strongly related to the bubble motions and fluid force is more dominant for the floating and sinking motions of a sphere in a fluidized bed comparing to contact force. Dependency on the superficial gas velocity is also investigated and both the numerical and experimental results show the fluctuation intensity of the dynamic vertical forces becomes larger with the increase of superficial gas velocity.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Online in situ viscosity determination in stirred tank reactors by
           measurement of the heat transfer capacity
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Martin Wunderlich, Patrick P. Trampnau, Emanuel F. Lopes, Jochen Büchs, Lars Regestein
      Viscosity plays an important role in a variety of biotechnological and chemical processes, such as in the production of biopolymers and in fermentations with filamentous microorganisms as well as in some dissolution, crystallization, and hydrogenation processes. Most of the established online methods for measuring the viscosity, however, struggle with the complexity of multiphase liquids like aerated liquids or suspensions and fermentation broths. This work presents a method to consider the viscosity of the whole reactor content regardless of its composition by means of calorimetric measurement of the heat transfer capacity (UA) and the use of a heat transfer model. Measurements were carried out with polyvinylpyrrolidone (PVP) model solutions (0–110g/L) in a 50L pilot scale stirred tank reactor with different viscosities (0.001–0.12Pa·s), mechanical power input (0.04–27kW/m³), and aeration rates (0–2vvm). The heat transfer capacity (UA) measurement by means of a calibration heater (1.25–12.5kW/m³) was found to be very precise (<1.5% standard deviation) and the online in situ determination of the viscosity fairly accurate (9.8% arithmetic mean error) in comparison to the offline measured viscosity. This suggests that the presented method is suited for online in situ viscosity determination in stirred tank reactors.


      PubDate: 2016-06-13T12:47:17Z
       
  • Editorial Board
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151




      PubDate: 2016-06-13T12:47:17Z
       
  • Insights into the hydrodynamic properties of slurry flow in a tubular
           photocatalytic reactor by PIV combined with LSIA
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Jiafeng Geng, Yechun Wang, Xiaowei Hu, Dengwei Jing
      Although turbulent flow is generally needed for good suspension of photocatalysts, lower flow rates are preferred from an economic viewpoint for energy-efficient operation. However, no experimental work has been conducted to reveal how photocatalyst particles move and distribute in a tubular photocatalytic reactor under mild operating conditions, which is critical for reactor design and configuration of the light concentration. In our study, the photocatalyst itself was employed as a tracer particle for Particle Image Velocity (PIV) measurement. PIV combined with a new laser sheet image analysis (LSIA) technology was employed to investigate both the particle velocity and number distribution in the tubular reactor. It was found that, in the inlet, a higher velocity distribution of fluid generally occurred in the lower part of the tube. However, in the middle and outlet regions of the tube, a higher velocity distribution existed in the upper part of the tube. LSIA investigation showed that the transport capacity of the fluid and the initial particle size distribution are two essential factors influencing particle number distribution in the suspension. Regardless of the particle size, the middle part of the reactor holds the maximum number of particles while the outlet has the minimum number of particles. In the inlet, both small and large particles show similar number distribution trends against the flow rate. However, in the middle part of the tube, the number of small particles decreases with the flow rate while the number of the large particles shows the opposite trend. The difference in velocity distribution along the radial direction also significantly affects the particle distribution. One interesting finding is that, regardless of the particle size, the number of particles in the upper part of the tube is always higher than that in centre. Stokes’ drag law and the Saffman lift force were employed to explain this experimental finding. In the last section, the correlation between particle distribution and optical properties was numerically investigated by a modified differential approximation (MDA) method.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Segregation and dispersion of binary solids in liquid fluidised beds: A
           CFD-DEM study
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Zhengbiao Peng, Jyeshtharaj B. Joshi, Behdad Moghtaderi, Md. Shakhaoath Khan, Geoffrey M. Evans, Elham Doroodchi
      Liquid fluidised beds often operate with particles of different sizes and densities, encountering partial or complete segregation of solid particles at certain operating conditions. In this study, the segregation and dispersion of binary particle species of the same size but different densities in liquid fluidised beds have been investigated based on the analysis of computational fluid dynamics – discrete element method (CFD-DEM) simulation results. The vertical fluid drag force acting on the particles was found to be responsible for the particle segregation. The mechanisms governing the particle dispersion strongly depended upon the solid–liquid two-phase flow regime, which transited from pseudo-homogeneous to heterogeneous when the superficial liquid velocity reached a certain value. In the homogeneous or pseudo-homogeneous flow regime (Re p≤40, ∈ L, ave≤0.74), particle collisions acted as the main mechanism that drove the dispersion of particles. However, after the system became heterogeneous, the magnitude of the vertical collision force decreased towards zero and correspondingly, the magnitude of the vertical fluid drag force was approaching that of the particle net weight force as the superficial liquid velocity increased. Therefore, in the heterogeneous flow regime (Re p>40, ∈ L, ave>0.74), the local turbulence of the fluid flow and particle collisions (if there were any) were found to be the main mechanisms that drove the dispersion of particles in all directions. The dispersion coefficient of individual particles varied significantly throughout the system in the heterogeneous flow regime. The simulation results reasonably agreed with the experimental data and the prediction results by existing correlations.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Fabrication and characterization of novel hollow fiber catalytic packing
           of PFSA–PES–ZrO2 (shell)–TiO2 (core) solid superacid via
           wet-spinning method
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Chen-Hao Ji, Shuang-Mei Xue, Zhen-Liang Xu, Xiao-Hua Ma
      In this work, a novel hollow fiber catalytic packing (HFCP) was fabricated of ZrO2 (shell)/TiO2 (core) (TZ) solid superacid nanoparticles, perfluorinated sulfonic acid resin (PFSA) and polyethersulfone (PES) via wet-spinning method. TZ was a homemade binary solid superacid nanoparticles with core–shell structure using superfine titania (5nm) as the core and mesoporous tetragonal phase zirconia as the shell. It was synthesized through the hydrolysis of zirconium oxychloride in the presence of titania nanoparticles and cetyltrimethylammonium bromide (CTAB) hexagonal crystals covered on the titania core and followed by calcination and acidification. HFCPs demonstrated well catalytic performance in the esterification test of ethanol and acetic acid due to the superacid sites on the surface of TZ and PFSA polymer chain. And the superacid sites on the PFSA polymer chain could be sufficiently exposed by the embedding of the nanoparticles. At the same time, HFCPs also showed ultrahigh recovery which was more than 99.5% in 6 runs because of the well integrality benefited from the wet-spinning method. The specific surface area (SSA) and pore size distribution were analyzed by N2 adsorption–desorption, the result showed that the SSA of HFCPs decreased with the increasing of the PFSA additive amount. The SSA of the HFCP with the best catalytic performance could be up to 90.60m2/g, in which the PFSA weight proportion was 13%. The XRD pattern and HRTEM image showed the HFCPs i.e. the zirconia shell of TZ formed uniform tetragonal phase. Other characterizations such as FT-IR, XPS, SEM and TEM were utilized to determine the chemical composition and morphology of the HFCPs and TZ, the results showed the novel catalytic packing was a suitable catalyst for the acid catalyzed reactions.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • In-situ grown molybdenum sulfide on TiO2 for dye-sensitized solar
           photocatalytic hydrogen generation
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Ghodsieh Malekshoar, Ajay K. Ray
      Molybdenum sulfide was loaded on TiO2 by an in-situ solar photo-deposition method over a dye synthesized photocatalytic process using Eosin Y (EY) as a photo-sensitizer and tri-ethanolamine (TEOA) as an electron donor. (NH4)2MoS4 was also used as a precursor. The effect of molybdenum sulfide as a co-catalyst was investigated. The proposed noble-metal-free photocatalytic system exhibited high efficiency for H2 evolution. A systematic statistical design of experimental analysis was employed to explore the impact of various parameters and to subsequently optimize the photocatalytic hydrogen production. TEOA, EY and (NH4)2MoS4 concentrations as well as pH of the solution were selected as the four factors in the study, whereas the amount of hydrogen produced after 3h of solar irradiation was considered as the response. The possible mechanism for the in-situ solar photo-deposition method was also proposed.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Mixing performance evaluation of additive manufactured milli-scale
           reactors
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Mihret Woldemariam, Roman Filimonov, Tuomas Purtonen, Joonas Sorvari, Tuomas Koiranen, Harri Eskelinen
      The mixing performance of three passive milli-scale reactors with different geometries was investigated at different Reynolds numbers. The effects of design and operating characteristics such as mixing channel shape and volume flow rate were investigated. The main objective of this work was to demonstrate a process design method that uses on Computational Fluid Dynamics (CFD) for modeling and Additive Manufacturing (AM) technology for manufacture. The reactors were designed and simulated using SolidWorks and Fluent 15.0 software, respectively. Manufacturing of the devices was performed with an EOS M-series AM system. Step response experiments with distilled Millipore water and sodium hydroxide solution provided time-dependent concentration profiles. Villermaux–Dushman reaction experiments were also conducted for additional verification of CFD results and for mixing efficiency evaluation of the different geometries. Time-dependent concentration data and reaction evaluation showed that the performance of the AM-manufactured reactors matched the CFD results reasonably well. The proposed design method allows the implementation of new and innovative solutions, especially in the process design phase, for industrial scale reactor technologies. In addition, rapid implementation is another advantage due to the virtual flow design and due to the fast manufacturing which uses the same geometric file formats.


      PubDate: 2016-06-13T12:47:17Z
       
  • Modeling of mass-transfer in bubbly flows encompassing different
           mechanisms
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Roland Rzehak
      Models proposed to describe the liquid side mass transfer coefficient in absorption processes differ widely in such basic questions as on which of the local flow variables they are based. Comparison of different alternatives with experimental data taken from the literature suggests that there are two basic mechanisms, a laminar and a turbulent one, each of which dominates under suitable conditions. A dimensionless number that allows to identify the corresponding regimes is suggested together with a preliminary model encompassing both. New experiments will be needed to come to a final conclusion.


      PubDate: 2016-06-13T12:47:17Z
       
  • Modeling of non-Darcy flow through anisotropic porous media: Role of pore
           space profiles
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Maziar Veyskarami, Amir H. Hassani, Mohammad Hossein Ghazanfari
      Excess pressure drop induced by inertial effects limits the applicability of Darcy's law for modeling of fluid flow through porous media at high velocities. It is expected such additional pressure drop is influenced by pore/morphology of porous media. This work concerns with fundamental understanding of how throat curvature affects intrinsic properties of porous media at non-Darcy flow conditions using network modeling. Conical, parabolic, hyperbolic, and sinusoidal capillary ducts with three types of imposed anisotropy are used to construct the network in a more realistic manner. Solutions of one dimensional Navier–Stokes equation for incompressible fluid flow through converging/diverging pore geometries have been utilized to acquire the pressure drop versus volumetric flow rate to investigate the role of various pore space profiles on the properties of porous media, which make the results of this work different from previous studies in the literature. Macroscopic inherent parameters of porous media such as tortuosity, porosity, permeability as well as non-Darcy coefficient are evaluated as outputs of the model. It has been revealed that the non-Darcy coefficient mainly depends on throat curvatures while permeability is not. While average throat radius is constant, both permeability and non-Darcy coefficient are increasing with average body radius. Among induced anisotropies, alteration of throat radius is the most effective parameter on non-Darcy coefficient. Regarding the throat morphology, some new general correlations for predicting the non-Darcy coefficient as a function of porosity, tortuosity, permeability, and the ratio of diverging/converging tubes in the network have been proposed. Results of this study could help better understanding of how the morphology of pores/throats affects the non-Darcy coefficient.


      PubDate: 2016-06-13T12:47:17Z
       
  • Study of gas–liquid two-phase flow patterns of self-excited dust
           scrubbers
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Xiaochuan Li, Tao Wei, Dongxue Wang, Haibin Hu, Lingzhuo Kong, Wu Xiang
      Self-excited dust scrubbers are widely used in the purification of a high dust concentration. However, the existing research has been primarily focused on the macroscopic performance of the dust scrubbers and has neglected the gas–liquid two-phase flow patterns that are closely related to its dust collection principle. This paper employed high-speed photography technology to acquire video images of liquid-phase patterns and employed high-frequency acquisition technology to acquire the corresponding dynamic pressure signals of the gas-phase of the self-excited dust scrubber. Using the probability density distribution (PDD), wavelet analysis, and power spectral density (PSD) estimation, in combination with the dynamic image analysis of the gas–liquid two-phase flow, a quantitative study of the gas–liquid two-phase flow patterns of self-excited dust scrubbers was conducted. This study provides strong supporting data to overcome the bottleneck that limits theoretical studies on self-excited dust scrubbers.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Analysis of power consumption and gas holdup distribution for an aerated
           reactor equipped with a coaxial mixer: Novel correlations for the gas flow
           number and gassed power
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Nasim Hashemi, Farhad Ein-Mozaffari, Simant R. Upreti, Dae Kun Hwang
      The main objectives of this work were to study the gassed power consumption and the local gas holdup for an aerated coaxial mixer composed of a wall scraping anchor and a central impeller. The working fluids were viscous corn syrup solutions at different concentrations. The central impellers were downward pumping pitched blade turbine, upward pumping pitched blade turbine, and hydrofoil A310 impellers. A novel correlation was developed to estimate the gassed power drawn by the coaxial mixer as a function of the gas flow rate, central impeller type, rotational speeds of the anchor and central impeller, and the ungassed power consumption by the anchor and the central impeller. To obtain a master power curve, two new correlations were proposed for the generalized power number and gas flow number of the aerated reactor furnished with the coaxial mixer by incorporating the equivalent rotational speed for the coaxial mixer, speed ratio (central impeller speed/anchor speed), and the central impeller power fraction into these two correlations. The experimental data revealed that by increasing the gas flow rate, the aerated anchor power was increased whereas the gassed power uptake of the central impeller was decreased. It was found that at the higher fluid viscosity and beyond the critical speed ratio equal to 10, the anchor power was increased by increasing the speed ratio (i.e. reducing the anchor speed). To measure the distribution of the gas holdup throughout the aerated reactor, four electrical resistance tomography planes were installed around the reactor. The tomography data showed that the local gas holdup near the vessel wall was not improved by increasing the anchor speed.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Modelling soot deposition and monolith regeneration for optimal design of
           automotive DPFs
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Janez Lupše, Marina Campolo, Alfredo Soldati
      Diesel particulate filters (DPFs) are extruded monoliths comprising many square channels. The material of the monolith, and the size and shape of channels require optimization to guarantee best performances. In this work, we develop an original semi-analytical model to analyze filter behavior during both loading and regeneration operations. Fluid flow and pressure drop along/across monolith channels are calculated based on lubrication theory and Darcy sub-model. Time evolution of filter properties induced by soot deposition and cake formation is modelled using a unit collector sub-model. Cake burn-out and the thermal response of the monolith during the regeneration stage is modelled using a simplified soot combustion and heat transfer sub-model. The impact of channel number and size, filter hydraulic permeability and thermal capacity on back-pressure build-up, regeneration efficiency and risk of thermal failure are discussed to improve the design of automotive DPFs.


      PubDate: 2016-06-13T12:47:17Z
       
  • A small, well-mixed reactor for high throughput study of commercial
           catalyst pills
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Edward M. Calverley, Edward L. Lee, De-Wei Yin, Thomas J. Parsons
      Industrial catalyst development is benefiting from the use of high throughput research. This is typically accomplished by running large numbers of experiments in parallel, using common reactant feed manifolds and analytical systems. In order to fit within a reasonable laboratory footprint, high throughput reactors must be small, yet retain mass and heat transfer rates that allow gradientless operation. For heterogeneous catalytic reactions there are a number of high throughput systems available for testing powdered, or granular catalysts in banks of plug flow reactors, but no reports of CSTR systems capable of testing formed catalyst particles used in commercial fixed bed reactors. We describe the development and engineering characterization of a small prototype CSTR for testing whole catalyst particles. The reactor has inside dimensions of 6.35cm diameter by 2.8cm deep and shows well-mixed behavior, based on methane tracer studies. Sublimation of non-porous cylindrical naphthalene cylinders (7.5mm diameter by 7mm long) was used to characterize the solid–gas mass transfer coefficient. It was found that the prototype reactor exhibits mass transfer rates similar or higher than reported in the literature for the much larger traditional Carberry and Berty-style reactors. This makes the new device suitable for further development of high throughput arrays of CSTRs for testing commercial catalyst pills.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Oxidation of copper at high temperature as an example for gas-solid
           reactions in a downer reactor – experiments and model-based analysis
           
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Maximilian A. Schöß, Frank Schulenburg, Thomas Turek
      The kinetics of a gas-solid reaction at high temperatures were studied in a downer reactor of 2.8m length. As an example, the oxidation of copper particles was carried out at different wall temperatures (1073K–1323K), oxygen concentrations (14 Vol.-%–67 Vol.-%), and particle diameters (51μm–156μm). Although the residence time of the particles was of the order of 1–4s only, considerable copper conversions could be achieved. XRD, EDX and SEM analysis of the formed products revealed that single layer formation of cuprous oxide prevails up to oxygen concentrations of about 25 Vol.-%. At higher oxygen concentrations, double layer oxidation occurs with a second cupric oxide layer forming on top of cuprous oxide. The remaining core radius of unreacted copper was determined through a combination of density measurements, analysis of TPR spectra, and direct SEM observation. Although significant scattering of the individual measurements was observed, it could be shown by independent elemental analysis of the products that the average values from all measurements are reliable. For quantitative evaluation of the measurements we developed a one-dimensional downer reactor model which allowed to calculate the residence time and particle temperature as a function of reactor length. Using this information we derived solid state diffusion coefficients, the activation energies of which agreed well with literature data. Overall it could be shown that the progress of a gas-solid reaction in a downer reactor can be successfully described with a combination of experimental methods and subsequent model-based data analysis.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Investigation of the influence of viscoelastic behaviour on the agitation
           of non-Newtonian fluid flow
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): T. Reviol, S. Kluck, F. Genuit, V. Reim, M. Böhle
      The design process of mixers agitating non-Newtonian fluid flow is usually performed with several well-known correlation methods. These methods have been the issue of many studies of the last few decades, so they are well discovered and often extended. But these studies also disclose the dependency of the correlation methods on the rheology of the fluid flow. Due to the good applicability the discovered dependencies were often neglected. In this paper the existing methods will be investigated experimentally for agitating viscoelastic as well as viscoinelastic fluid flow to determine the influence of viscoelasticity on the power consumption of agitating non-Newtonian fluid flow.


      PubDate: 2016-06-13T12:47:17Z
       
  • Sensitivity of chemical-looping combustion to particle reaction kinetics
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): M.A. Schnellmann, S.A. Scott, G. Williams, J.S. Dennis
      A simple simulation for chemical-looping combustion (CLC) is discussed: two, coupled fluidised reactors with steady circulation of particles of oxygen carrier between them. In particular, the sensitivity of CLC to different particle kinetics is investigated. The results show that the system is relatively insensitive to different kinetics when the mean residence time of particles in each reactor is greater than the time taken for them to react completely.


      PubDate: 2016-06-13T12:47:17Z
       
  • PAT-based design of agrochemical co-crystallization processes: A
           case-study for the selective crystallization of 1:1 and 3:2 co-crystals of
           p-toluenesulfonamide/triphenylphosphine oxide
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): K.A. Powell, D.M. Croker, C.D. Rielly, Z.K. Nagy
      In this study, the selective crystallization and characterization of the stoichiometric forms of the p-toluenesulfonamide/triphenylphosphine oxide (p-TSA–TPPO) co-crystal system in acetonitrile (MeCN) is demonstrated using batch and semi-batch crystallizers. In the batch study, both 1:1 and 3:2 p-TSA–TPPO were successfully isolated as pure forms. However, process variability was observed in a few experimental runs. To address the batch process variability issue, a control strategy was implemented using temperature cycling, aided by in situ process analytical technologies (PAT) to convert from 3:2 to 1:1 p-TSA–TPPO. In the semi-batch co-crystallization studies, the two molecular co-formers, p-TSA and TPPO, were dissolved in MeCN and pumped separately to the crystallizer. Changing the flow rates of the respective active ingredients allowed control over the co-crystallization outcome, and presents as a promising opportunity for development of a continuous co-crystallization process.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Theoretical investigation on correlation between steric effects and
           selectivity in gas–solid chlorination of polyvinyl chloride
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Chenxi Cao, Qianli Yang, Ding Mao, Yi Cheng
      Gas–solid chlorination of polyvinyl chloride (PVC) enables environmentally friendly and cost-effective production of chlorinated polyvinyl chloride (CPVC) as a high performance material. For this reaction-controlled process, understanding the correlation between steric effects and selectivity in chlorination is the key to improve product quality and process efficiency. We performed density-functional theory (DFT) calculations on model compounds of PVC chain segments in order to provide a microscopic view of gas–solid PVC chlorination. The micro-selectivity was compared and steric effects were visualized. The results showed that radical substitution in gas–solid PVC chlorination is stereoselective because of steric effects, in which the microstructure-determined local chain conformation plays a governing role. In the chlorination to the first degree, the formation of –CH2–CCl2– is allowed by direct radical substitution because –CHCl– groups are not necessarily sterically blocked; heterotactic triads are the most reactive due to little steric hindrance of its stable conformation. In the chlorination to the second degree, steric effects of the additional chlorine in product lead to much higher reaction barrier for radical substitution. The γ carbon of –CHCl– group and the β carbon of –CCl2– group are sterically blocked. These molecular-level understandings of steric effects and selectivity in radical substitution during gas–solid PVC chlorination suggest that by properly choosing reaction temperature, initiation modes and PVC feedstock, the chlorination progress can be tuned to avoid undesired side reactions and improve product quality.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Prediction of conductive heating time scales of particles in a rotary drum
    • Abstract: Publication date: 2 October 2016
      Source:Chemical Engineering Science, Volume 152
      Author(s): Heather N. Emady, Kellie V. Anderson, William G. Borghard, Fernando J. Muzzio, Benjamin J. Glasser, Alberto Cuitino
      Modeling conductive heat transfer from rotary drum walls to a particle bed via discrete element method simulations, three time scales were determined: 1) the characteristic heating time of the bed, τ; 2) the particle thermal time constant, τ p ; and 3) the contact time between a particle and the wall, τ c . Results fall onto a monotonic curve of τ/τ c vs. ϕ (τ p /τ c ), with three heating regimes. At low ϕ, conduction dominates, and the system heats quickly as a solid body. At high ϕ, granular convection dominates, and the bed heats slowly at a nearly uniform temperature. At intermediate ϕ, the system heats as a cool core with warmer outer layers. The results of this work have important implications for improving the design and operation of rotary drums (e.g., energy-intensive calcination processes). By calculating τp and τ c from material and operating parameters, the characteristic heating time, τ, can be predicted a priori.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Removal of hydrogen sulfide by permanganate based sorbents: Experimental
           investigation and reactor modeling
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Edith Goldnik, Thomas Turek
      The removal of hydrogen sulfide from ambient air can be accomplished by porous adsorbents, which are impregnated with potassium permanganate. In this study such adsorbents were prepared by granulation on a pelletizing disk and characterized in breakthrough measurements with hydrogen sulfide. In these experiments different reaction times, pellet sizes, inlet concentrations and residence times were analyzed. To investigate the reaction process inside the pellet, microscopic analyses and REM/EDX element scans of reacted particles after different reaction times were performed. These results indicate that the reaction mainly proceeds at a rather sharp reaction front. As a first approach the shrinking core model was applied for the description of the breakthrough curves, showing already a good agreement with the experimental results. Additionally a volume reaction model was developed, which considers two consecutive reactions occurring in the whole particle volume. In contrast to the shrinking core model, the volume reaction model allows for describing the decrease of the measured position of the reaction zone in good agreement with the optical and elemental analyses of the reacted adsorbent pellets.
      Graphical abstract image

      PubDate: 2016-06-13T12:47:17Z
       
  • Hydrolysis kinetics of inulin by imidazole-based acidic ionic liquid in
           aqueous media and bioethanol fermentation
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Zhi-Ping Zhao, Xiao-Lan Wang, Gui-Yin Zhou, Yong Cao, Peng Lu, Wen-Fang Liu
      This article focused on the inulin-containing energy biomass, Jerusalem artichoke, to explore environment-friendly processes for bioethanol production. An imidazole-based acidic ionic liquid (VImaILs) was prepared as the catalyst of inulin hydrolysis in aqueous media. The hydrolysis kinetics was studied under different conditions. The kinetic parameters of hydrolysis by VImaILs and dilute sulfuric acid were estimated and compared. This work demonstrated that the hydrolysis rate of inulin into reducing sugars by VImaILs was obviously faster than that by the latter. The proposed kinetic model successfully predicted the inulin hydrolysis in wider ranges of experimental conditions. The hydrolysate was fermented into ethanol by Saccharomyces cerevisiae which activity was not inhibited by the VImaILs. The conversion efficiency of inulin-type sugars to ethanol was greater than 92.5% of the theoretical yield. And the ethanol production capacity reached 123.76g/(L). This system integrated the chemical and biological processes to prepare ethanol in an environment-friendly way.
      Graphical abstract image

      PubDate: 2016-05-15T05:48:41Z
       
  • Activity based kinetics of CO2–OH− systems with Li+, Na+ and
           K+ counter ions
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): Shahla Gondal, Hallvard F. Svendsen, Hanna K. Knuutila
      In this work the applicability of activity based kinetics for the absorption of CO2 into hydroxide and carbonate solutions is discussed. It was found by several authors that reaction rate constants based on concentration strongly depend both on concentration and the counter ion present in solution. In this study experimental kinetics data for LiOH, NaOH and KOH from the literature were reevaluated using activity based kinetics. It is observed that the use of activities instead of concentrations eliminates the effect of both concentration and counter ion on the rate constant and an expression for the activity based second order rate constant is derived. The activities used in this work were calculated with the electrolyte-NRTL model which predicts well the equilibrium partial pressure of CO2, the composition of the liquid phase and the apparent Henry’s law constant. The calculated activity coefficients were used to predict the activity based rate constant and CO2 flux from the concentration based second order kinetic constant at infinite dilution ( k OH − ∞ ). The infinite dilution rate constant, combined with e-NRTL based activities of CO2 and hydroxyl ion, predicted the CO2 absorption fluxes within 14% AARD showing that the proposed approach can be used for prediction of activity based rate constants and the CO2 absorption flux for any system involving the reaction of CO2 with hydroxyl ion.


      PubDate: 2016-05-15T05:48:41Z
       
  • Sub-grid models for heat transfer in gas-particle flows with immersed
           horizontal cylinders
    • Abstract: Publication date: 12 September 2016
      Source:Chemical Engineering Science, Volume 151
      Author(s): W.A. Lane, A. Sarkar, S. Sundaresan, E.M. Ryan
      Simulating full-scale heated fluidized bed reactors can provide invaluable insight to the design process. Such simulations are typically computationally intractable due to their complex multi-physics and various length-scales. While it may be possible to simulate some large-scale systems, they require significant computing resources and do not lend themselves well to design optimization methods. To overcome these problems coarse-grid simulations can be used with supplementary constitutive sub-grid models to approximate the unresolved physics. This study details the development, implementation, and verification of a sub-grid model for heat transfer in gas-particle flows with immersed horizontal cylinders. Using the two-fluid model for multiphase flow, small periodic unit-cell domains were simulated over a wide range of flow and geometry conditions. The results were filtered and fit using nonlinear regression to build a Nusselt correlation based on the solids fraction, solids velocity, cylinder geometry (diameter and spacing), and the Peclet number. The proposed model is highly nonlinear and includes power-law contributions from each parameter. The model was verified using a nearly orthogonal experiment design where the input parameters were varied randomly to generate combinations not previously considered. The predicted filtered Nusselt numbers agreed well with the observed (simulated) values. Work is on-going to further expand the capabilities of the model, including 3D simulations, vertical cylinders, and uncertainty quantification.


      PubDate: 2016-05-15T05:48:41Z
       
 
 
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